Roofing felt compositions are suitably used to lay on top of buildings to provide waterproofing. Roofing felt compositions are widely known and for example described in the Shell Bitumen Industrial Handbook, ISBN-0-95-16625-1-1, London, 1995, chapter 8.1.3, pages 208-253.
WO-A-99/011737 disclose a bitumen composition for producing a road topping containing a Fischer-Tropsch paraffin (FT paraffin) as an additive. According to this publication the Fischer-Tropsch paraffin additive is a mixture of more than 90% n-alkanes and the remainder being iso-alkanes. A commercial available Fischer-Tropsch additive is SASOBIT, which is marketed by Sasol Wax Ltd.
WO-A-02/16499 also discloses a bitumen composition for producing a road topping containing a Fischer-Tropsch paraffin (FT paraffin) as an additive.
In the field of roofing felt applications it is important to achieve a so-called phase inversion. This is achieved by adding a polymer to the bitumen. It is an object to add as little polymer to the bitumen due to its costs. The content of polymer will be dependent on the quality of the bitumen used.